Ridge roof ventilation

Good afternoon

The roof in my house needed to be replaced. We contracted a near by company which completed the job in a day or so. They replaced the Roof Redge with a newer product and want to know your input. Apparently this is what it is being used now, the old roof has a fiverglass type of material that I could see from inside the attic.
The product they used looks like a piece of plastic nothing else to it.
Here is my concern: the roof has been installed for 2 weeks now, and every time it rains I can see small drop of water in the underside of this Ridge Edge. They are telling me that this is normal because the root needs ventilation. I am not sure if they just did not install this thing correctly or missing.
Is it possible that water could get inside of the roof with any of these Roof Ridge products?
I will post the type of product they used as soon as I know.
The product installed was: Cobra Ridge Vent 3(exaust vent).